(1) Field of the Invention
The present invention relates to a signal processing technology for echo signals acquired via a probe of an ultrasonic diagnostic apparatus, in particular, to a data processing technology for acoustic line data generated based on the echo signals, and a data conversion technology from acoustic line data to display data.
(2) Description of the Related Art
An ultrasonic diagnostic apparatus which is capable of observing a subject without invasion and in real time has become an essential existence in the medical field. Recently, while there have been increasing attempts to improve the function of an ultrasonic diagnostic apparatus, there have been efforts to reduce the cost for operating the apparatus, as well.
As an example of such efforts to reduce the cost as described above, an ultrasonic diagnostic apparatus which performs a signal processing unit for generating acoustic line data in a software achieved by a personal computer is suggested (for example, refer to Japanese Laid-Open Patent publication No. H11-329).
FIG. 1 is a block diagram showing a functional structure of a conventional ultrasonic diagnostic apparatus 100. As shown in FIG. 1, the ultrasonic diagnostic apparatus 100 comprises: an overall control unit 71, a signal processing unit 72, an acoustic line data control unit 73, an acoustic line data memory unit 74, a two-dimensional display control unit 75, a display unit 76, a three-dimensional display control unit 77 and a three-dimensional data memory unit 78.
The overall control unit 71 is a functional unit that controls the overall operations of the ultrasonic diagnostic apparatus 100, such as a micro computer equipped with ROM or RAM.
The signal processing unit 72 performs a phasing addition and a filter process for echo signals received via a probe, and generates acoustic line data which indicates tomographic image information.
The acoustic line data control unit 73 controls writing-in and reading-out of the acoustic line data, generated by the signal processing unit 72, into the acoustic line data memory unit 74. And, the acoustic line data control unit 73 transmits the generated acoustic line data to the two-dimensional display control unit 75.
The acoustic line data memory unit 74 is a memory apparatus that memorizes acoustic line data following the direction of the acoustic line data control unit 73, such as RAM.
The two-dimensional display control unit 75 receives acoustic line data transmitted from the acoustic line data control unit 73, and performs a two-dimensional coordinate conversion process and an interpolating process for the acoustic line data. And, the two-dimensional display control unit 75 generates display data. And, the two-dimensional display control unit 75 transmits the display data to the display unit 76 and the three-dimensional display control unit 77.
The display unit 76 displays a tomographic image and the like in a monitor (for example, CRT: not shown in figures), based on the display data outputted by the two-dimensional display control unit 75 or the three-dimensional display control unit 77.
The three-dimensional display control unit 77 takes in the display data transmitted by the two-dimensional display control unit 75, and generates volume data and image (written as a “three-dimensional image” below) data that describes volume data.
The three-dimensional data memory unit 78 is, for example, RAM, and memorizes the volume data generated by the three-dimensional display control unit 77.
Next, the operations performed by the ultrasonic diagnostic apparatus 100 will be explained by classifying each representative operational mode. Each operational mode will be further divided into the two modes: a “live mode” and a “cine mode”. Here, a “live mode” means a mode that generates acoustic line data from echo signals received via a probe (and further holds the generated acoustic line data in the acoustic line data memory unit 74), and displays a tomographic image and the like in real time. A “cine mode” means a mode that reads out the acoustic line data, once held in such “live mode” as described above, from the acoustic line data memory unit 74 and displays the tomographic image and the like.
(B Mode)
A “B mode” is a mode that displays the strength of a reflective wave with brightness.
A “live mode” of the “B mode” is a mode that processes echo signals received via a probe, and displays a “B mode” image in the display unit 76 in real time.
The operations performed by the “live mode” of the “B mode” are as following.
Acoustic line data indicating tomographic image information is generated by performing a phasing addition and a filter process for echo signals received via a probe in the signal processing unit 72. The generated acoustic line data is memorized by the acoustic line data memory unit 74, via the acoustic line data control unit 73; and at the same time, the generated acoustic line data is transmitted to the two-dimensional display control unit 75.
The two-dimensional display control unit 75 (i) performs a two-dimensional coordinate conversion process and an interpolating process for acoustic line data, (ii) generates display data for displaying a “B mode” image, and (iii) transmits the display data to the display unit 76. The display unit 76 displays the “B mode” image, based on the display data received from the two-dimensional display control unit 75.
On the other hand, the “cine mode” of the “B mode” reads out the acoustic line data memorized in the “live mode”, and displays the “B mode” image in the display unit 76, as well as such “live mode” as described above.
The operations performed by the “cine mode” of the “B mode” are as following.
The acoustic line data control unit 73 reads out the acoustic line data memorized by the acoustic line data memory unit 74, and transmits the acoustic line data to the two-dimensional display control unit 75. Here, the operations of the two-dimensional display control unit 75 and the display unit 76 are the same as those of the “live mode” of the “B mode”.
(Color Mode)
A “color mode” is a mode that displays a blood flow image (a tomographic image indicating the high and low of the blood flow speed with a plurality of colors, which is also called a “color flow mode”). The “live mode” of the “color mode” processes echo signals received from a probe, and generates a blood flow image (also called the “color mode” image), and displays the blood flow image in the display unit 76 in real time.
The operations performed by the “live mode” of the “color mode” are as following.
The signal processing unit 72 performs a phasing addition, a filter process, and a frequency analysis process for echo signals received via a probe, and generates acoustic line data indicating blood flow information. The generated acoustic line data is memorized by the acoustic line data memory unit 74, via the acoustic line data control unit 73; and at the same time, the generated acoustic line data is transmitted to the two-dimensional display control unit 75.
The two-dimensional display control unit 75 performs a two-dimensional coordinate conversion process and an interpolating process for acoustic line data, generates display data for displaying a “color mode” image, and transmits the display data to the display unit 76.
On the other hand, the “cine mode” of the “color mode” reads out the acoustic line data memorized by the “live mode”, and displays the “color mode” image in the display unit 76, based on the generated display data, as well as such “live mode” as described above.
The operations performed by the “cine mode” of the “color mode” are as following.
The acoustic line data control unit 73 reads out the acoustic line data memorized by the acoustic line data memory unit 74, and transmits the acoustic line data to the two-dimensional display control unit 75. Here, the operations of the two-dimensional display control unit 75 and the display unit 76 are the same as those of the “live mode”.
Also, in the operations performed by the “color mode”, the operations of the “B mode” are concurrently performed; and in general, the “color mode” image is displayed overlapping the “B mode” image.
(M Mode)
An “M mode” is a mode that displays a time displacement image of tomographic image information in the same acoustic line position in the display unit 76.
The “live mode” of the “M mode” processes echo signals received via a probe to generate an “M mode” image, and displays the “M mode” image in the display unit 76 in real time.
The operations performed by the “live mode” of the “M mode” are as following.
First, the signal processing unit 72 performs a phasing addition and a filter process for echo signals received via a probe, and generates acoustic line data.
Next, the generated acoustic line data is memorized by the acoustic line data memory unit 74, via the acoustic line data control unit 73; and at the same time, the generated acoustic line data is transmitted to the two-dimensional display control unit 75.
The two-dimensional display control unit 75 performs a two-dimensional coordinate conversion process and an interpolating process for acoustic line data, and generates display data for displaying an “M mode” image, that is, display data where ultrasonic acoustic line information of the same acoustic line position is arranged in the order of the time string. And, the two-dimensional display control unit 75 transmits the display data to the display unit 76. The display unit 76 displays the “M mode” image according to the received display data.
On the other hand, the “cine mode” of the “M mode” reads out the acoustic line data memorized by the “live mode”, and generates display data. And, the “cine mode” of the “M mode” transmits the display data to the display unit 76. The display unit 76 displays the “M mode” image, based on the received display data.
The operations performed by the “cine mode” of the “M mode” are as following.
First, the acoustic line data control unit 73 reads out the acoustic line data memorized by the acoustic line data memory unit 74, and transmits the acoustic line data to the two-dimensional display control unit 75.
Here, the operations of the two-dimensional display control unit 75 and the display unit 76 are the same as those of the “live mode” of the “M mode”.
(Color M Mode)
A “color M mode” is a mode that displays a time displacement image of blood flow information in the same acoustic line position. The “live mode” of the “color M mode” processes echo signals received via a probe, and displays the “color M mode” image in the display unit 76 in real time.
The operations performed by the “live mode” of the “color M mode” are as following.
First, the signal processing unit 72 performs a phasing addition, a filter process and a frequency analysis process for echo signals received via a probe, and generates acoustic line data indicating blood flow information.
Next, the generated acoustic line data is memorized by the acoustic line data memory unit 74, via the acoustic line data control unit 73; and at the same time, the generated acoustic line data is transmitted to the two-dimensional display control unit 75.
The two-dimensional display control unit 75 performs a two-dimensional coordinate conversion process and an interpolating process for acoustic line data, and generates display data for displaying a “color M mode” image, that is, display data where blood flow acoustic line information of the same acoustic line position is arranged in the order of the time string. And, the two-dimensional display control unit 75 transmits the display data to the display unit 76.
On the other hand, the “cine mode” of the “color M mode” reads out the acoustic line data memorized by the “live mode”, and displays the “color M mode” image, based on the display data, in the display unit 76.
The operations performed by the “cine mode” of the “color M mode” are as following.
First, the acoustic line data control unit 73 reads out the acoustic line data indicating blood flow information memorized by the acoustic line data memory unit 74, and transmits the acoustic line data to the two-dimensional display control unit 75.
Here, the operations of the two-dimensional display control unit 75 and the display unit 76 are the same as those of the “live mode”. Also, in the operations performed by the “color M mode”, the operations of the “M mode” are concurrently performed; and in general, the “color M mode” image is displayed overlapping the “M mode” image.
(Doppler Mode)
A “Doppler mode” is a mode that displays a time displacement image of the Doppler spectrum of the same acoustic line position.
The “live mode” of the “Doppler mode” processes echo signals received via a probe, and displays the “Doppler mode” image in the display unit 76 in real time.
The operations performed by the “live mode” of the “Doppler mode” are as following.
First, the signal processing unit 72 performs a phasing addition, a filter process, and a Fourier analysis process for echo signals received via a probe, and generates acoustic line data indicating Doppler spectrum information.
Next, the generated acoustic line data is memorized by the acoustic line data memory unit 74, via the acoustic line data control unit 73; and at the same time, the generated acoustic line data is transmitted to the two-dimensional display control unit 75.
The two-dimensional display control unit 75 performs a two-dimensional coordinate conversion process and an interpolating process for acoustic line data, and generates display data for displaying a “Doppler mode” image, that is, display data where Doppler spectrum acoustic line information of the same acoustic line position is arranged in the order of the time string. And, the two-dimensional display control unit 75 transmits the display data to the display unit 76.
On the other hand, the “cine mode” of the “Doppler mode” generates the display data by reading out the acoustic line data memorized by the “live mode”, and displays the “Doppler mode” image in the display unit 76.
The operations performed by the “cine mode” of the “Doppler mode” are as following.
First, the acoustic line data control unit 73 reads out the acoustic line data indicating Doppler spectrum information memorized by the acoustic line data memory unit 74, and transmits the acoustic line data to the two-dimensional display control unit 75. Here, the operations of the two-dimensional display control unit 75 and the display unit 76 are the same as those of the “live mode” of the “Doppler mode”.
(3D Live Mode)
A “3D live mode” is a mode that simultaneously generates (a) a tomographic image by processing echo signals received via a 3D probe in real time, and (b) a three-dimensional image by a volume rendering process, said volume being generated from a plurality of tomographic image group which is a volume data set, and simultaneously displays a tomographic image and a three-dimensional image in the display unit 76.
The operations performed by the “3D live mode” are as following.
First, the signal processing unit 72 performs a phasing addition and a filter process for echo signals received via a probe, and generates acoustic line data. Next, the generated acoustic line data is transmitted to the two-dimensional display control unit 75, via the acoustic line data control unit 73.
The two-dimensional display control unit 75 performs a two-dimensional coordinate conversion process and an interpolating process for acoustic line data, and generates display data. And, the two-dimensional display control unit 75 transmits the display data to the display unit 76 and the three-dimensional display control unit 77.
The three-dimensional display control unit 77 takes in the display data, and generates volume data on the three-dimensional data memory unit 78. And, the three-dimensional display control unit 77 generates three-dimensional image data by a volume rendering, and transmits the three-dimensional image data to the display unit 76.
Finally, the display unit 76 simultaneously displays the tomographic image and the three-dimensional image data.
(Multi Planner Reconstruction (MPR) Mode)
An “MPR mode” is a display mode that observes volume data on the three-dimensional data memory unit 78 as a three-dimensional image or a cross-sectional image from an arbitrary viewpoint, said volume data being generated by the “3D live mode”.
The operations performed by the “MPR mode” are as following.
First, by using the volume data on the three-dimensional memory unit 78 and according to the radial direction provided by the overall control unit 71, the three-dimensional display control unit 77 performs a volume rendering, and generates three-dimensional image data. And, the three-dimensional display control unit 77 transmits the three-dimensional image data to the display unit 76.
Next, by using the volume data memorized on the three-dimensional data memory unit 78, the three-dimensional display control unit 77 generates cross-sectional image data whose volume is sliced by a predetermined plate provided by the overall control unit 71, and transmits the cross-sectional image data to the display unit 76.
Finally, the display unit 76 performs a display, according to the three-dimensional image data and the cross-sectional image data.
Although specific explanations will be omitted here, the “MPR mode” is capable of an operation to delete a part of the volume data. In such case as described above, the “MPR mode” generates and displays the three-dimensional image and the cross-sectional image for the volume data other than the deleted part.
A structure of the conventional ultrasonic diagnostic apparatus can be briefly divided into the following two units: (i) a signal processing unit that generates acoustic line data by performing a phasing addition and a filter process for echo signals received via a probe, and (ii) a backend unit that memorizes the acoustic line data outputted from the signal processing unit and reads out the acoustic line data to display.
As shown in FIG. 1, the backend unit includes the following functional units: an acoustic line data control unit 73, an acoustic line data memory unit 74, a two-dimensional display control unit 75, a display unit 76, a three-dimensional display control unit 77 and a three-dimensional data memory unit 78.
The problems of the backend unit 79 of the conventional ultrasonic diagnostic apparatus 100 will be explained in detail as following.
The image quality of a two-dimensional tomographic image outputted by the ultrasonic diagnostic apparatus 100 is greatly influenced not only by the process algorithm of the signal processing unit but also by the process algorithm of the backend unit. In particular, the quality of the tomographic image and the like is greatly influenced by the interpolating process for a coordinate conversion, the frame interpolating process and the like which are necessary in the process of converting acoustic line data to display data.
For example, the two-dimensional display control unit 75 needs a coordinate conversion to the display area of the display unit 76, according to the physical form of the probe connected to the ultrasonic diagnostic apparatus; however, a convex probe or a sector probe and the like need a polar-orthogonal coordinate conversion. In such polar-orthogonal coordinate conversion, the acoustic line data which is original data does not appear on the grid of the orthogonal coordinate. Thus, it is necessary to generate the display data on the orthogonal coordinate by the interpolating process.
Although there are various kinds of interpolating methods for the interpolating process algorithm, such as a linear interpolating method and an upsampling filter method, each method has advantages and disadvantages.
In the case of the linear interpolating method, a calculation cost is not necessary, but the image quality is not very good. In the case of the upsampling filter method, the calculation cost increases, depending on the number of filter taps, but the image quality is improved than the linear interpolating method.
Thus, in order to achieve as good an image quality as possible by efficiently utilizing the hardware resource of the apparatus within the limit, the quality of the tomographic image should be optimized by enabling the dynamic change of the interpolating process algorithm, depending on the physical form of the probe and the frame rate of the tomographic image data outputted by the signal processing unit. However, according to the conventional structure, such functions as described above are performed as a functional block which performs a solid process. Thus, it is difficult to perform such processes as described above.
The quality of the three-dimensional image outputted by the ultrasonic diagnostic apparatus is greatly influenced by the process algorithm of the backend unit, as well as the quality of the two-dimensional tomographic image. The three-dimensional image generation process requires the two processes of a volume generation and rendering the generated volume. Such generation process and rendering process are performed by the three-dimensional display control unit 77.
Since the volume generation has the same problem as the one described in the quality of the two-dimensional tomographic image, the explanation will be omitted here.
As the volume rendering process performs the calculation process of a mass volume, the balance between the rendering algorithm which is related with the image quality and the processing time is always essential.
Another problem is the functional block division of the backend unit of the conventional ultrasonic diagnostic apparatus.
FIG. 2 is a diagram showing the further specific functional structures of the acoustic line data control unit 73 and the acoustic line data memory unit 74.
As shown in FIG. 2, an individual functional block is provided for each operational mode. The acoustic line data control unit 73 includes: the “B mode” acoustic line data control unit 73a, the “color mode” acoustic line data control unit 73b, the “M mode” acoustic line data control unit 73c, the “color M mode” acoustic line data control unit 73d and the “Doppler mode” acoustic line data control unit 73e. The acoustic line data memory unit 74 includes: the “B mode” acoustic line data memory unit 74a, the “color mode” acoustic line data memory unit 74b, the “M mode” acoustic line data memory unit 74c, the “color M mode” acoustic line data memory unit 74d and the “Doppler mode” acoustic line data memory unit 74e. 
Here, in the case of the “B mode”, only the “B mode” acoustic line data memory unit 74a is used among the blocks included in the acoustic line data memory unit 74; and the other blocks are not used.
Also, in the case of the “color mode”, only the two blocks of the “B mode” acoustic line data memory unit 74a and the “color mode” acoustic line data memory unit 74b are used; and it is the same in the case of the other operational modes.
In addition, depending on the operational mode of the ultrasonic diagnostic apparatus, not only the use situation of the acoustic line data memory unit 74, but also the use situation of the three-dimensional data memory unit 78 differs. For example, in the case of displaying only the “B mode” image, the three-dimensional data memory unit 78 is not used at all.
Moreover, the coordinate conversions of the two-dimensional display control unit 75 and the three-dimensional display control unit 77 are essentially the same; however, at present they are performed as different functional blocks.
As described above, the functional block division of the backend unit of the conventional ultrasonic diagnostic apparatus is inefficient; and as a result, the cost is increased.
Japanese Laid-Open Patent publication No. H11-329 discloses an ultrasonic diagnostic apparatus which comprises a personal computer and a software that performs a signal process. And, the Japanese Laid-Open Patent publication No. H11-329 further discloses a fast performance of a signal process by the use of a CPU of a higher-efficiency, and a multiple process of a plurality of functional modules by implementing and multitask-operating the software in an object-oriented manner.
However, such problem as described above is not solved; and the advantage of the ultrasonic diagnostic apparatus comprising a software is not fully utilized.